That written permission is worthless unless notarized & verified (which isn't going to happen for ordinary things) because you can just write it yourself. And

That written permission is worthless unless notarized & verified (which isn't going to happen for ordinary things) because you can just write it yourself. And you don't need a passport. I've never met a company that will require full KYC-level video-identification with you on every call. You say that you're you (it doesn't matter whether you actually are you), you give them the secret code and they're happy.